Improvement in manufacture of gas for burning and lighting



NITED STATES PATENT OFFICE.

THOMAS B. REDWOOD, OF FAIRLAWN FINOHLEY, ENGLAND.

IMPROVEMENT IN MANUFACTURE OF GAS FOR BURNING AND LIGHTING;

Specification forming part of Letters Patent N 0. 169,037, dated October19, 1875; application filed April 24, 1875.

To all whom it may concern: 7

Be it known that I, THOMAS BOVERTON REDWOOD, of Fairlawn Finchley, inthe county of Middlesex, England, a subject of the Queen of GreatBritain, have invented or discovered new and useful Improvements in theMannfacture of Gas for Burning, to produce light or heat; and I, thesaid THOMAS BOVERTON REDWOOD, do hereby declare the nature of the saidinvention, and in what manner the same is to be performed, to beparticularly described and ascertained in and by the following statementthereof-that is to say:

This invention has for its object the production of a permanent gas,consisting of a mixture of water-gas, and a gas rich in carbon, producedfrom petroleum and other hydrocarbon oils, including the oils obtainedfrom coal, shale, peat, and other sources. As met with in commerce theseoils often contain solid hydrocarbons, such as paraffine. They aremixtures in various proportions of several proximate constituents,differing in density and volatility, but consisting, for the most part,of carbon and hydrogen in proportions, which, in some of theirconstituents, accord with, and in others differ but slightly from,

those in which the same elements exist in olefiant gas, or otherpermanent hydrocarbon gases, which are the most valuable light-producingconstituents, of the richest and best description of coal-gas, orof gassuitable for burning as a source of light.

It has long been known that by the application of heat the hydrocarbonoils, such as I have alluded to, may be made to yield a gas tolerablyrich in carbon. The principal difficulty experienced in getting a goodpermanent gas, rich in carbon, from hydrocarbon oils, has been that ofso regulating and applying the heat as to insure the conversion of theoils, or their vapors, into permanent gas without, at the same time,causing much of the carbon, which is the true source of light during thecombustion of gas, to be deposited in a solid shape. It is necessary toapply a temperature above that of visible redness in order to change thevapor of the oil into permanent gas, and there appears to be but a smallrange of temperatures through which that change can be effected incontact with most solid substances, without converting part of the oilinto a species of tar, and at the same time causing a deposition ofsolid carbon from the gaseous product.

By the method hereinafter described the liquid hydrocarbonsalluded to,or their gaseous products, together with water-gas, may be subjected toa higher temperature than it has been found practicable to apply to themby the usual methods, without causing a deposition of solid carbon.Liquid hydrocarbons, or their vapors, when heated in contact withmetallic copper or an alloy of copper, such as brass or gun metal, willbear the application of a higher temperature than can be applied to themby contact with other substances with out depositing solid carbon, andthe range of temperature, at which the conversion of the oils intopermanent gas, without loss of carbon, takes place, is thus enlarged, sothat a more uniform and satisfactory result may be practically attained,and an important economy effected.

I have found that if the liquid hydrocarbons or their vapors beintroduced into a hot chamber, together with a permanent gas, such aswater-gas, which is either previously or immediately heated to atemperature, which, in

a metal or other solid body, would be repre-,

sented as that of bright redness, the vapors of the hydrocarbon oilsmay, under these circumstances, be subjected in contact with copper, oran alloy of copper, to a cherry-red heat, and will thus be morecompletely and satisfactorily converted into a permanent gas than wouldotherwise be the case.

My improved process for the manufacture of gas for burning is foundedupon the foregoing facts. The vapors of liquid or solid hydrocarbons,such as I have described, are converted into permanent gas with littleor no deposition of carbon, with the intervention of water-gas, by thefollowing method: The water-gas I use is obtained by the well-knownprocess of passing superheated steam over the surface of incandescentcarbon at a high temperature, when a mixture of hydrogen gas andcarbonic oxide is produced together with some carbonic acid, which isremoved by means of slaked lime before using the gas. The purifiedwater-gas, so produced, is introduced simultaneously with thehydrocarbon oil, or its vapors, both being gradually and continuouslyintroduced, as the conversion large a heating-surface as passible tothevapor. In this way the cylinder and its contents may be maintained ata temperature of from bright redness to, and including what is usuallycalled, a cherry-red heat, at which latter temperature it may be keptwithout causing any material deposition of carbon from the gas produced;and in order to'prevent too great a reduction of temperature, by theintroduction of the water-gas, I convey this gas through red-hot tubesbefore it enters the cyl- 1nder or convertin g-chamber. The proportionof water-gas used in this process, in relation to the hydrocarbon oils,may be regulated by suitable valves or taps, so as to yield a mixed gashaving an illuminating power, such as may be required for burning as asource of light, or otherwise, it may be further mixed with a richergas, made without or with a smaller quantity of water-gas or withwatergas itself.

The gas produced by this method should be passed through a condenser, orscrubber, or both, for the purpose of removing the visible vapor ofunconverted oil, a portion of which wlll be carried over in the process,and as this unconverted oil may constitute a material part of the oilused in the process, it is important that efficient means. should beadopted for recovering it, so that it may be reintroduced into the hotcylinder and finally converted into permanent gas. I have found that theoily particles, the presence of which 1 gives tothe gas the character ofvisible vapor, are retained in suspension in the gas and carrled to aconsiderable distance while the gas is rapidly flowing through thepipes, but they soon subside when the gas is at rest, as occurs in thegasometer. It will be found advantage ous as a means of promoting theseparation and collection of the suspended oil particles after passingthe gas throughthe ordinary tubular condensers, such as are used atgasworks, to allow it to pass in small jets through water or petroleum,using in the latter case one of the less volatile varieties of petroleumand avoiding the renewal of the water or petroleum unnecessarily, asthese liquids, when used in excess, and before they have becomesaturated by contact with the gas, would dissolve out some of the mostvaluable constltuents of the gas. After having deprived the gas ofsuspended particles of unconverted 011,1t should be passed through a drylime purifier to insure the absence of carbonic acid,

but no other purification will be necessary, except when a crudehydrocarbon oil, which may contain a little sulphur, has been em: ployedin the process, in which case the lime purifier should have a layer ofoxide of iron at the bottom for the removal of sulphureted hydrogen. Thegeneral arrangement of apparatus required for conducting the processneed not differ much, excepting in its greater simplicity and muchsmaller extent from that adopted in the manufacture of coal-gas. Thewater-gas may be made by passing superheated steam through a cylinderfilled with charcoal or other form of carbon, such as coke, breeze, orpeat charcoal, kept at a full red heat. An ordinary gas-retort may beused for thispurpose, but there is some advantage in having the cylinderset in a vertical position and the steam made to enter at the bottomwhile the water-gas passes ed at the top. If the carbonaceous matterused should contain any sulphur, a little sulphureted hydrogen would beformed, which, as well as any carbonic acid that may be present, must beremoved from the water-gas, and for this purpose it will be desirable tohave a layer of oxide of iron, such asis commonly used in gaspurification, at the bottom of the lime purifier, by which thecarbonicacid is .to be taken out. The water-gas thus produced andpurified may be used at once or stored ina gasometer for use. p Theconversion of hydrocarbon oils into permanent gas with the interventionof water-gas may also beefi'ected in a gas-retort, if this be linedinside with copper or an alloy of copper, filled with scraps, turnings,wire, or wiregauze of the same metal, and provided with the means ofintroducing a regulated'supply of the hydrocarbon oils, and ofwater-gas. The exit-pipe,

by which the gas is conveyed away fromthe.

hot cylinder or retort, to the extent to which such pipe is exposed to astrong heat, should be of the same material as the cylinder or its innersurface, or otherwise some of the gases richest in carbon may bedecomposed when subjected to a high temperature, and deprived of part oftheir carbon, and to a correspond ing extent of their light-producingpower. If the arrangements of existing gas'works be not utilized oradopted, cylinders may be used of any convenient size or form, in which,how-v ever, it is desirable to provide for the means of heating.them'throughout to the required extent, and these cylinders may beeither. made entirely of copper or an alloy of copper, or they may havean outside covering of other material to protect the metal Within fromthe destructive 'efl'ects of the; fire. When pre-. viously-heatedwater-gas is used in the pro cess, the fire by which the cylinderorconverting-chamber is heated may be madefto heat pipes through whichthe water gas isconveyed to the hot chamber, and it willbe foundadvantageous, for the preservation of these pipes, that they should beembedded in and surrounded by powdered lime to prevent their oxidationand destruction from this cause. In fitting up apparatus specially forthe purpose of making gas by the processes herein described, it will befound advantageous to have the condensing and oil-separatingarrangements at a higher level than that of the converting-cylinders sothat the oil that is condensed and separated from the gas after leavingthe converting-cylinder may be brought back to the cylinder by its owngravity.

What I claim is- The hereinbetbre-described improvement in themanufacture of permanent gas rich in carbon, which consists in bringinghydrocarbon vapor, together with water-gas, into contact with alargely-extended and highly-heated surface of copper or an alloy ofcopper.

T. BOVEBTON REDWOOD.

Witnesses:

WILMER M. HARRIS, JOHN DEAN,

No. 17 Gracechurch Street, London.

